Abstract: The leading cause of death in diabetic patients is cardiovascular disease (CVD). Our long-term goal is to identify new therapeutic targets for the prevention of CVD in diabetic patients. In the last grant cycle, we identified the enzyme, flavin-containing monooxygenase 3 (FMO3) as a potential mediator of diabetes associated cardiovascular disease. FMO3 is suppressed by insulin and increased in the livers of obese/diabetic subjects; moreover, knockdown of FMO3 completely prevented the development of hyperglycemia, hyperlipidemia and atherosclerosis in insulin resistant mice. The FMO3 pathway is exciting because of the striking magnitude of the effects observed in insulin resistant mice and the fact that early studies suggest that FMO3 is also dysregulated in diabetic humans. Moreover, the fact that FMO3 was identified via non-biased approaches suggests that it may be a central pathway discovered only now that the proper tools have become available. The overall goal of this proposal is to define the mechanistic links in the diabetes/FMO3/atherosclerosis pathway, focusing on the transcription factor, Sterol Regulatory Element Binding Protein (SREBP)-2, which we have identified as a mediator of FMO3's actions. Our aims are as follows: (1) determine how insulin and diabetes regulate FMO3; (2) define the product or target of the FMO3 enzyme required for its downstream effects; and (3) define the mechanism by which FMO3 alters cholesterol metabolism to induce SREBP-2. We expect that these studies will provide the mechanistic detail necessary to determine if and how the FMO3 pathway can be manipulated for therapeutic use.